Explosive and thermic compositions or charges – Containing inorganic nitrogen-oxygen salt
Reexamination Certificate
2001-11-01
2004-01-27
Carone, Michael J. (Department: 3641)
Explosive and thermic compositions or charges
Containing inorganic nitrogen-oxygen salt
C149S019100
Reexamination Certificate
active
06682616
ABSTRACT:
TECHNICAL FIELD WHERE THE INVENTION BELONGS
The present invention relates to a gas generating agent for generating an operation gas in pretensioner systems that are mounted on, for example, automobiles and aircrafts in order to protect human bodies.
BACKGROUND OF THE INVENTION
Heretofore, a seat belt is disposed on vehicles such as automobiles for protecting drivers against impact shocks upon collision. To further increase safety improvement, a pretensioner system, which comprises “a pretensioner”, i.e. an emergency pull-in device disposed to a seat belt roll-up device for retracting the seat belt, has been prevailing recently. And by the pretensioner, the seat belt is retracted instantly to hold passenger's body.
In such a pretensioner, since the seat belt has to be retracted instantaneously, a gas generated upon combustion of a gunpowder is utilized as a power source. That is, a piston inside a cylinder is instantaneously moved by the combustion gas from a gas generating agent, and a power is supplied to the pretensioner by the movement of a cable connected at one end to the piston.
As the gas generating agent used for the pretensioner, for example, JP-A 49-50619 discloses that a single base propellant, a double base propellant, and a triple base propellant, using nitrocellulose as a base agent, can be used.
Such well-known conventional propellants have high combustibility but have a problem that gases after combustion contain a great amount of noxious CO gases. And with an increasing consciousness for safety, pretensioners have tended to be used not only for a driver seat but also for a passenger seat and rear seats, so that an amount of CO gases is no longer negligible.
Further, because these well-known existing propellants are based on nitric ester such as nitrocellulose and nitroglycerin, there is the problem of poor thermal stability. These are not preferable in the pretensioner desired to exhibit stable performance for a prolonged period of time.
At present, however, a method of improving gases after combustion of the single base propellant, the double base propellant, and the triple base propellant, using nitrocellulose as the base agent, and a method of improving thermal stability of such propellants, have not been specifically provided.
Further, JP-A 2-293389 discloses, for example, a gas generating agent comprising cellulose acetate and ammonium perchlorate. Certainly, this makes possible to improve thermal stability and reduce an amount of CO gases. However, when cellulose acetate is used as a binder, procedures such as extrusion molding and cutting operation are very difficult and producing and processing are also difficult. In addition, when ammonium perchlorate is used as an oxidizing agent, generation of chlorine-containing gases such as hydrogen chloride in gases after combustion may be a problem.
DISCLOSURE OF THE INVENTION
In view of the above, it is an object of the present invention to provide a gas generating composition superior in thermal stability, capable of decreasing an amount of CO gases, excellent in producing and processing, and capable of reducing chlorine-containing gases if required, by combination of a highly thermal stabilized binder and an oxidizing agent as major components.
Another object of the present invention is to provide a pretensioner system using the gas generating composition described above.
The present inventors found that by combining a highly thermal stabilized binder with an oxidizing agent as major components, it is possible to provide a gas generating composition superior in thermal stability, capable of decreasing an amount of CO gases, excellent in producing and processing, and capable of reducing chlorine-containing gases if required, thus arriving at the completion of the present invention.
That is, the present invention provides a gas generating composition for use in a pretensioner, which is superior in thermal stability, capable of reducing CO gases and excellent in producing and processing. In addition, the present invention provides a gas generating composition which is superior in thermal stability, capable of reducing CO gases and capable of reducing chlorine-containing gases.
The gas generating composition of the present invention can be applied to a seat belt device for a vehicle passenger, comprising a belt, a roll-up device for rolling up the belt, a pretensioner for retracting the belt at an emergency, a gas generating agent and a power transmitting unit for driving the pretensioner.
Further, it can also be applied to a method of restraining a passenger's body comprising the steps of actuating the pretensioner at an emergency by using a gas generating agent, and retracting the belt in a seal belt system for a vehicle passenger comprising a belt, a roll-up device for rolling up the belt, a pretensioner for retracting the belt at an emergency, a gas generating agent and a means for transmitting power by a generated gas thereby driving the pretensioner.
The gas generating composition for use in a pretensioner according to the present invention is capable of improving the thermal stability of a gas generating agent, capable of decreasing an amount of CO gases, excellent in producing and processing, and capable of reducing chlorine-containing gases if required, by combination of a highly thermal stabilized binder and an oxidizing agent as major components. Accordingly, the safety of a vehicle passenger can be improved and a highly reliable pretensioner system can be obtained.
PREFERRED EMBODIMENT OF THE INVENTION
The gas generating composition used in one embodiment of the present invention comprises a binder and an oxidizing agent.
The binder, can include at least one compound selected from the group consisting of cellulose acetate butyrate (CAB) carboxymethyl cellulose sodium (CMC-Na), hydroxyethyl cellulose (HEC), hydroxypropyl cellulose (HPC), methyl cellulose (MC), ethyl hydroxyethyl cellulose (EHEC), carboxymethyl ethyl cellulose (CMEC), starch, guar gum, polyvinyl alcohol (PVA), polyacrylamide, silicone, acrylic ruber, polystyrene (PS), polyacrylonitrile (PAN), polyvinyl chloride (PVC), hydroxy-terminated polybutadiene (HTPB), carboxy-terminated polybutadiene (CTPB) and glycidyl azide polymer (GAP). Because these compounds are superior in thermal stability and producing and processing (handling easiness in manufacturing) to known nitrocellulose and cellulose acetate (CA), the thermal stability of the gas generating composition and producing and processing the gas generating composition are also improved.
The binders described above may be used singly or in combination thereof. By use of a plurality of binders, handling easiness during manufacturing, such as the viscosity of the gas generating composition and the hardness, flexibility etc. of the molded article can be improved. For example, the molded article is easily broken or disrupted when cellulose acetate is used alone, but the handling qualities thereof can be improved by mixing it with cellulose acetate butyrate.
The content of the binder in the gas generating composition is varied depending on the type and amount of the nitrogen-containing compound, oxidizing agent, chlorine-neutralizing agent, ignition improver, stabilizer, flash reducing agent, plasticizer, deterrent, glazing, curing agent, bonding agent, crosslinking agent, metal fuel, combustion catalyst and aging inhibitor as well as oxygen balance, but the content of the binder is preferably 7 to 30% by weight, particularly preferably 8 to 25% by weight.
Further, the gas generating composition of the present invention can be blended with an oxidizing agent.
The oxidizing agent is preferably one or more compounds selected from the group consisting of ammonium salts, alkali metal salts and alkaline earth metal salts of chloric acid, perchloric acid, nitric acid and nitrous acid, more preferably one or more members selected from the group consisting of ammonium perchlorate, potassium perchlorate, sodium perchlorate, potassium nitrate, sodium nitrate and strontium nitrate. These oxid
Osawa Hideya
Yamato Yo
Carone Michael J.
Daicel Chemical Industries Ltd.
Felton Aileen B.
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